Split your kids into multiple groups. The goal of the game is very simple; the groups need to compete to build the tallest, freestanding structure they can. Here's the catch: groups can only use the materials they have on hand. They cannot retrieve materials from anyone or anywhere else, they can only use what is on their person at the time of the game.

After it looks like groups are wrapping up, call time and have groups step away from their structures. Review and measure the structures one by one, making sure they are standing by themselves. Give a prize to the winning group. 

Then review the main lesson of the game: As a leader, you must utilize what you have. Ask the participants if at any point, they were wishing they had some other material that another group had, such as a large water bottle or any other object. They naturally will. What you are teaching from this game is that wishing you had another team's resources or people doesn't help you at all as a leader. You should focus on making the most of the teammates and materials you already have.